Electrophotographic photoreceptor and charge-transporting material for electrophotographic photoreceptor

ABSTRACT

A charge transporting material for use in an electrophotographic photoreceptor, which comprises a compound represented by the formula (1); and an electrophotographic photoreceptor using this charge transporting material. As the electrophotographic photoreceptor using the charge transporting material, there are illustrated, for example, a lamination type photoreceptor having a charge generating layer  2  and a charge transporting layer  3  and, as needed, an interlayer  7,  and a single layer type photoreceptor. In the formula, R 1  to R 5  each independently represents a hydrogen atom, an alkyl group, a halogen atom, an alkoxy group, an aryl group or a substituted aryl group, and R 6  represents a hydrogen atom, an alkyl group, an aryl group or a substituted aryl group.

TECHNICAL FIELD

The present invention relates to an electrophotographic photoreceptorwhich is favorably used as a photoreceptor in a copying or recordingapparatus based on electrophotographic system, such as anelectrophotographic copier, a laser beam printer, a printer having aliquid crystal shutter, an LED printer or the like and to a chargetransporting material to be used in the photoreceptor.

BACKGROUND ART

As photoconductive materials in an electrophotographic photoreceptor,there have conventionally been widely used inorganic materials such asselenium, selenium-tellurium, diarsenic triselenide, cadmium sulfide,zinc oxide or amorphous silicon. An electrophotographic photoreceptorusing such inorganic photoconductive material, however, has involvedsuch problems as that it has a practically poor flexibility, that it issensitive to heat or mechanical impact, that its production cost is toohigh, and that it has some toxicity.

In recent years, various photoreceptors using organic materials havebeen proposed for solving these problems and have been put intopractical use. As one embodiment of the electrophotographicphotoreceptors utilizing the organic material, an embodiment wherein theorganic photoconductive body is functionally separated into a part ofexerting charge transporting function and a part of exerting chargegenerating function, a so-called function separated type photoreceptor,has been exceedingly examined and the function separated typephotoreceptor also has been made practicable (e.g., U.S. Pat. No.3,791,826, etc.). In the function separated type electrophotographicphotoreceptor, a material showing a large carrier-generating efficiency(the term “carrier” means charge; hereinafter the same) is used as acharge generating material, and there is a possibility that a highlysensitive electrophotographic photoreceptor can be obtained by combiningthe charge generating material with a substance showing a high chargetransporting ability as a charge transporting material.

Characteristic properties required for the charge transporting materialto be used in such electrophotographic photoreceptor are to effectivelyreceive carriers generated in the charge generating material uponirradiation with light in an electrical field and allow the carriers tomove rapidly through the photoreceptor layer for rapid disappearance ofsurface potential. The speed for the carrier to move per unit electricalfield is called “carrier mobility”. High carrier mobility means that thecarrier rapidly moves through the charge transporting layer. Thiscarrier mobility is inherent to the charge transporting material.Therefore, in order to attain high carrier mobility, it is necessary touse a material showing high carrier mobility but, under the presentcircumstances, the carrier mobility is still at an insufficient level.

Also, in the case where the charge transporting material is used bydissolving it in an organic solvent together with a binder polymer toapply, it is required to form a uniform organic thin film withouteduction of crystals or formation of pinholes. Because, electricbreakdown would take place at a place of such fine crystals or pinholesupon application of a high electrical field to the photoreceptor, ornoise would be generated at the place. Further, even when characteristicproperties of both of the charge generating material and the chargetransporting material are good, it is important that carrier injectionfrom the charge generating material to the charge transporting materialbe conducted with a high efficiency. Also, in the case where the chargegenerating material and the charge transporting material are used indifferent layers, it is important that carrier injection from the chargegenerating layer to the charge transporting layer be conducted with ahigh efficiency. This charge injection depends upon a property of theinterface between the charge generating material (or charge generatinglayer) and the charge transporting material (or charge transportinglayer), and varies depending upon kinds of materials constituting theinterface.

As has been described hereinbefore, the charge transporting material isrequired to satisfy various requirements. Thus, charge transportingmaterials having varying properties have been developed, andelectrophotographic photoreceptors using them have been put intopractical use. As the conventionally proposed charge transportingmaterials for the electrophotographic photoreceptor, there may beillustrated triarylamine dimmer derivatives represented by the followinggeneral formula (A) as described in JP-B-58-32372:

wherein X represents o-CH₃, m-CH₃, p-CH₃, o-Cl, m-Cl or p-Cl.

Also, as other examples, there may be illustrated m-diaminobenzenederivatives represented by the following general formula (B) or (C) asdescribed in JP-A-1-142642, JP-A-5-88389, etc.:

wherein Rs each independently represents an alkyl group, an alkoxy groupor a halogen atom, and each phenyl group may not be substituted or maybe substituted by any possible number of substituents, with thesubstituents being the same or different from each other;

wherein Ar represents a non-condensed or condensed polycyclichydrocarbyl group other than a phenyl group, Rs may be the same ordifferent from each other and each represents a hydrogen atom, a halogenatom, a cyano group, a nitro group, a substituted or unsubstituted alkylgroup, an alkoxy group, an aryl group, an aryloxy group, analkylmercapto group, an amino group or a methylenedioxy group.

As further examples, there may be illustrated 1, 1, 4,4-tetraphenyl-1,3-butadiene derivatives represented by the followinggeneral formula (D) and tetraphenyl-1,3,5-hexatrienes represented by thefollowing general formula (E) (e.g., JP-B-7-21646 and JP-B-5-19701):

wherein R represents a di-lower alkylamino group, and R′ represents ahydrogen atom or a di-lower alkylamino group;

wherein Ar₁, Ar₂, Ar₃ and Ar₄ each represents an aryl group optionallyhaving a substituent, with at least one of Ar₁ to Ar₄ being an arylgroup having a substituted amino group as the substituent, and nrepresents 0 or 1.

Also, many hydrazone derivatives have been described in, for example,JP-B-55-42380, JP-A-57-101844, JP-A-54-150128 and JP-A-61-23154.

However, only a few numbers of the many reported compounds havesatisfactory characteristic properties or conditions practicallyrequired as a photoreceptor when used in a light-sensitive layercomposed of a combination of a charge generating layer and a chargetransporting layer. That is, there are involved various problems. Forexample, crystals are educed after film formation or, even when filmformation is well conducted, a sufficient surface potential is notretained in the dark, and the surface potential fails to be fullydecreased after irradiation with light (low sensitivity and highresidual potential).

The invention has been made in consideration of the above-describedproblems, and objects of the invention are to provide a chargetransporting material for use in an electrophotographic photoreceptor,which can provide a practical electrophotographic photoreceptor showinga high charge mobility, educing no crystals and forming no pinholes uponfilming, and providing a light-sensitive layer which is stable and has ahigh sensitivity and a low residual charge; and to provide anelectrophotographic photoreceptor using this charge transportingmaterial.

As a result of eager studies and intensive investigations to solve theabove-mentioned problems, the inventors have found that theabove-mentioned problems can be solved by incorporating in anelectrophotographic photoreceptor, or by using as a charge transportingmaterial, the compound represented by the following formula (1) andreached to the invention.

DISCLOSURE OF THE INVENTION

The invention is an electrophotographic photoreceptor or a chargetransporting material described below as [1] to [5]:[1] An electrophotographic photoreceptor which contains a compoundrepresented by the formula (1):

wherein R¹ to R⁵ each independently represents a hydrogen atom, an alkylgroup, a halogen atom, an alkoxy group, an aryl group or a substitutedaryl group, and R⁶ represents a hydrogen atom, an alkyl group, an arylgroup or a substituted aryl group.[2] An electrophotographic photoreceptor which contains a compoundrepresented by the above formula (1) as a charge transporting materialin the light-sensitive layer provided on an electrically conductivesupport.[3] An electrophotographic photoreceptor of lamination type havingprovided on an electrically conductive support a charge generating layerand a charge transporting layer, which contains a compound representedby the above formula (1) as a charge transporting material.[4] An electrophotographic photoreceptor of single layer type havingprovided on an electrically conductive support a layer containing both acharge generating material and a charge transporting material, whichcontains a compound represented by the above formula (1).[5] A charge transporting material for use in an electrophotographicphotoreceptor, which contains a compound represented by the aboveformula (1).

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a partial schematic cross-sectional view of a lamination typeelectrophotographic photoreceptor, which shows one example of thelayered structure of the lamination type electrophotographicphotoreceptor using a charge transporting material of the invention.

FIG. 2 is a partial schematic cross-sectional view of a lamination typeelectrophotographic photoreceptor, which shows another example of thelayered structure of the lamination type electrophotographicphotoreceptor using a charge transporting material of the invention.

FIG. 3 is a partial schematic cross-sectional view of a single layertype electrophotographic photoreceptor, which shows an example of thelayered structure of the single layer type electrophotographicphotoreceptor using a charge transporting material of the invention.

FIG. 4 is a partial schematic cross-sectional view of a lamination typeelectrophotographic photoreceptor, which shows an example of the layeredstructure of the lamination type electrophotographic photoreceptor ofthe invention having an interlayer.

FIG. 5 is a partial schematic cross-sectional view of a lamination typeelectrophotographic photoreceptor, which shows another example of thelayered structure of the lamination type electrophotographicphotoreceptor of the invention having an interlayer.

FIG. 6 is a partial schematic cross-sectional view of a single layertype electrophotographic photoreceptor, which shows an example of thelayered structure of the single layer type electrophotographicphotoreceptor of the invention having an interlayer.

SPECIFIC EMBODIMENT OF THE INVENTION

The invention is described in more detail below. The electrophotographicphotoreceptor of the invention contains a compound represented by theforegoing formula (1) (hereinafter referred to as “compound (1)”), andthe charge transporting material of the invention for use in anelectrophotographic photoreceptor contains a compound represented by theforegoing formula (1). In the formula (1), an alkyl group of R¹ to R⁵and R⁶ may be straight, branched or cyclic, and is exemplified by analkyl group containing 1 to 6 carbon atoms. Specific examples thereofinclude a methyl group, an ethyl group, a n-propyl group, a 2-propylgroup, a n-butyl group, a 2-butyl group, an isobutyl group, a tert-butylgroup, a n-pentyl group, a 2-pentyl group, a tert-pentyl group, a2-methylbutyl group, a 3-methylbutyl group, a 2,2-dimethylpropyl group,a n-hexyl group, a 2-hexyl group, a 3-hexyl group, a tert-hexyl group, a2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a2-methylpentan-3-yl group, a cyclopropyl group, a cyclobutyl group, acyclopentyl group and a cyclohexyl group. As the alkyl group, an alkylgroup containing 1 to 3 carbon atom is preferred.

Also, examples of a halogen atom of R¹ to R⁵ include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Also, an alkoxy group of R¹ to R⁵ may be straight, branched or cyclic,and is exemplified by an alkoxy group containing 1 to 6 carbon atoms.Specific examples thereof include a methoxy group, an ethoxy group, an-propoxy group, a 2-propoxy group, a n-butoxy group, a 2-butoxy group,an isobutoxy group, a tert-butoxy group, a n-pentyloxy group, a2-methylbutoxy group, a 3-methylbutoxy group, a 2,2-dimethylpropyloxygroup, a n-hexyloxy group, a 2-methylpentyloxy group, a3-methylpentyloxy group, a 4-methylpentyloxy group, a 5-methylpentyloxygroup and a cyclohexyloxy group. As the alkoxy group, an alkoxy groupcontaining 1 to 3 carbon atom is preferred.

Further, as the aryl group represented by R³ to R⁵ and R⁶, there areillustrated, for example, an aryl group containing 6 to 14 carbon atoms,and specific examples thereof include a phenyl group, a 1-naphthylgroup, a 2-naphthyl group and an anthryl group. As the substituted arylgroup, there are illustrated those aryl groups which are formed bysubstituting at least one hydrogen atom of said aryl group by asubstituent such as an alkyl group, an aryl group, an alkoxy group, ahalogenated alkyl group, a halogen atom, an amino group or a substitutedamino group and those aryl groups which are formed by substituting twoadjacent hydrogen atoms of said aryl group by a substituent such asanalkylenedioxy group. Additionally, the alkyl group, aryl group, alkoxygroup and halogen atom referred to as the substituents of the aryl groupare the same as those described hereinbefore. As the halogenated alkylgroup, there are illustrated those halogenated alkyl groups which areformed by halogenation (e.g., fluorination, chlorination, bromination oriodation) for substituting at least one hydrogen atom of said alkylgroup by a halogen atom and which have 1 to 6, preferably 1 to 3, carbonatoms. Specific examples thereof include a chloromethyl group, abromomethyl group, a trifluoromethyl group, a 2-chloroethyl group, a3-bromopropyl group and a 3,3,3-trifluoropropyl group. As thealkylenedioxy group, there are illustrated, for example, alkylenedioxygroups having 1 to 3 carbon atoms, and specific examples thereof includea methylenedioxy group, an ethylenedioxy group, a trimethylendioxy groupand a propylenedioxy group. As the substituted amino group, there areillustrated those which are formed by substituting one or two hydrogenatoms of an amino group by a substituent such as an alkyl group or anaryl group, with the alkyl group and the aryl group being also the sameas mentioned above. Specific examples of an aryl group substituted by analkyl group include an o-tolyl group, a m-tolyl group, a p-tolyl group,a 2,4-dimethylphenyl group and a mesityl group. Specific examples of anaryl group substituted by an aryl group include a biphenyl group etc.

Specific examples of the compound (1) are shown in the followingTable 1. However, it is needless to say that these are mere examples ofthe compound (1) of the invention, and the compound (1) of the inventionis not limited to only those shown in the following table. TABLE 1Number of Substituents Compound (1) R¹ to R⁵ n R⁶ 1-1 H H H 1-2 Me (R¹or R⁵) 1 H 1-3 R²═Me or 1 H R⁴═Me 1-4 R³═Me 1 H 1-5 R¹═R²═Me or 2 HR⁴═R⁵═Me 1-6 R³═Cl 1 H 1-7 R³═OMe 1 H 1-8 R³═Ph 1 H 1-9 H Me 1-10 H Et1-11 H Ph 1-12 R³═Me 1 Ph 1-13 R³═Me 1 p-Tol 1-14 H α-Nap 1-15 H β-Nap

In the above table, Me represents a methyl group, Ph a phenyl group, Etan ethyl group, p-Tol a 4-methylphenyl group, α-Nap a 1-naphthyl group,and β-Nap a 2-naphthyl group. Also, the number of substituents, n, is anumber of substituents of R¹ to R⁵ per phenyl group.

It suffices that at least one of compounds (1) be incorporated in theelectrophotographic photoreceptor of the invention, and two or more ofthem may be incorporated in combination.

The compound (1) may be prepared by, for example, a process shown by thefollowing scheme 1.

In the above formulae (2) to (7), R¹ to R⁶ are the same as definedhereinbefore, R⁷ represents a methyl group or an ethyl group, and Xrepresents a chlorine atom, a bromine atom or an iodine atom.

That is, first, a halogen-substituted stilbene derivative (4) issynthesized by Wittig-Horner reaction [1] between a carbonyl compound(2) and a p-halogen-substituted benzyl phosphate (3) or [2] between ap-halogenobenzaldehyde (5) and a benzyl phosphate (6). Subsequently,four times the equivalent amount of the thus obtainedhalogen-substituted stilbene derivative (4) is subjected to a couplingreaction with phenylenediamine (7) in the presence of a palladiumcatalyst and a base to synthesize an end product of compound (1) withease. Solvents to be used for these reactions and reaction conditionsmay be employed according to conventionally known processes. Also, theabove-mentioned coupling reaction (carbon-nitrogen bond-formingreaction) using the palladium catalyst may be conducted according toknown processes described in, for example, JP-A-2002-187894, Journal ofOrganic Chemistry (J. Org. Chem.), 2000, vol. 65, p. 5327, Perspectivesin Organopalladium Chemistry for the XXI Century (ELSEVIER, p. 125),etc.

It is preferred that, in the electrophotographic photoreceptor of theinvention, at least one of the thus-obtained compounds (1) be containedas a charge transporting material. As the type of theelectrophotographic photoreceptor of the invention, there areillustrated a lamination type electrophotographic photoreceptor havingprovided on an electrically conductive support at least a chargegenerating layer and a charge transporting layer as light-sensitivelayers and a single-layer type electrophotographic photoreceptor havingprovided on an electrically conductive support at least a layercontaining both a charge generating material and a charge transportingmaterial as a light-sensitive layer. Constitution of each of theseelectrophotographic photoreceptors of the invention are furtherdescribed by reference to Figures. FIGS. 1 and 2 illustrate a partialschematic cross-sectional view of a lamination type electrophotographicphotoreceptor. A light-sensitive layer 4 of the photoreceptor in FIG. 1is constituted by a charge generating layer 2 provided on anelectrically conductive support 1 and a charge transporting layer 3provided on the charge generating layer 2. In a photoreceptor shown inFIG. 2, a charge transporting layer 3 is provided on an electricallyconductive support 1, and a charge generating layer 2 is formed on thecharge transporting layer 3. Thus, in the lamination typeelectrophotographic photoreceptor, either of the charge generating layerand the charge transporting layer may be provided nearer to the support,but the photoreceptor shown in FIG. 1 wherein the charge transportinglayer is provided on the charge generating layer is more preferred.Also, the single-layer type electrophotographic photoreceptor is aphotoreceptor wherein a light-sensitive layer 4 containing at least botha charge generating material 6 and a charge transporting material 5 isprovided on an electrically conductive support 1 as shown by the partialschematic cross-section in FIG. 3. Additionally, it suffices for theelectrophotographic photoreceptor of the invention to contain thecompound (1) in the photoreceptor, but it is preferred to incorporatethe compound (1) as a charge transporting material in a light-sensitivelayer provided on an electrically conductive support of theelectrophotographic photoreceptor.

The electrophotographic photoreceptor of the invention will bespecifically described by reference to, first, the lamination typeelectrophotographic photoreceptor. In the lamination typeelectrophotographic photoreceptor, a charge generating layer and acharge transporting layer are provided on an electrically conductivesupport. First, the charge transporting layer is described below. Thecharge transporting layer can be provided by vacuum-depositing thecompound (1) as such on an electrically conductive support or on thecharge generating layer, or by dissolving or dispersing the compound (1)and a binder polymer in a proper solvent, coating the solution ordispersion on the electrically conductive support or on the chargegenerating layer, then drying.

As the binder polymer, any of those which have conventionally been usedas binder polymers for a photoreceptor may be used. Needless to say, anyof binder polymers which have conventionally been used for forming thecharge transporting layer may be used. Specific examples of the binderpolymer to be used for forming the charge transporting layer includeinsulating thermoplastic or thermosetting resins such as (meth)acrylicresins such as polyacrylate and polymethacrylate, polyamide resin,acrylonitrile resin, vinyl chloride resin, acetal resin, butyral resin,vinyl acetate resin, polystyrene resin, polyolefin resin, celluloseester, phenol resin, epoxy resin, polyester resin, alkyd resin, siliconeresin, polycarbonate resin, polyurethane resin, polyimide resin, andcopolymers or derivative resins thereof; and photo-setting insulatingresins. In addition to these resins, there are illustrated organicphoto-conductive polymers such as polyvinylcarbazole,polyvinylanthracene and polyvinylpyrene. These binder polymers may beused independently or in a proper combination of two or more of them. Ofthese binder polymers, a polycarbonate resin having the repeating unitrepresented by, for example, the following formula (F) is preferred:

polycarbonate wherein R¹¹ and R¹² each may be the same or different andeach represents a hydrogen atom, a lower alkyl group containing 1 to 4carbon atoms, a lower alkoxy group containing 1 to 4 carbon atoms or aphenyl group optionally substituted by a halogen atom, or may beconnected to each other to form a ring, R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸,R¹⁹ and R²⁰ each independently represents a hydrogen atom, a halogenatom, an alkyl group, an alkoxy group or a phenyl group optionallyhaving a substituent, and n represents a positive integer.

Of the polycarbonates represented by the above formula (F), specificpreferred examples include bisphenol A type polycarbonates having therepeating unit represented by the following formula (G) (e.g., Iupilon Eseries made by Mitsubishi Gas Chemical Company, Inc.) and bisphenol Ztype polycarbonates having the repeating unit represented by thefollowing formula (H) (e.g., Iupilon Z series made by Mitsubishi GasChemical Company, Inc.) and copolymer carbonates having bisphenol A,bisphenol Z and biphenol carbonate as constitutional units (e.g., seeJP-A-4-179961).

bisphenol A type polycarbonate

bisphenol Z type polycarbonate

Specific examples of the foregoing biphenol copolymer carbonate includebisphenol/biphenyl type polycarbonate resins represented by thefollowing formula (I) (wherein n/n+m being preferably 0.1 to 0.9), and amore specific example is a bisphenol A/biphenyl type polycarbonate resinrepresented by the following formula (J) (wherein n/n+m being 0.85).

bisphenol/biphenyl type copolymerized polycarbonate

bisphenol A/biphenyl type copolymerized polycarbonate

(n/n+m=0.85)

wherein R¹¹ to R²⁰ are the same as defined hereinbefore, and R²¹, R²²,R²³, R²⁴, R²⁵, R²⁶, R²⁷ and R²⁸ each independently represents a hydrogenatom, a halogen atom, an alkyl group, an alkoxy group or a phenyl groupoptionally having a substituent, with two of R²¹R²², R²³, R²⁴, R²⁵, R²⁶,R²⁷ and R²⁸ being optionally connected to each other independently toform a ring, and n and m each represents a number of moles of theabove-described repeating unit.

In addition to the above-described bisphenol/biphenyl typepolycarbonate, a polycarbonate whose repeating unit is represented bythe following formula (K) (JP-A-6-214412), a polycarbonate whoserepeating unit is represented by the following formula (L)(JP-A-6-222581), a high molecular binder having introduced thereinto asiloxane unit represented by the following formula (M) or (N)(JP-A-5-88398, JP-A-11-65136) and the like can also be preferably used.

In the above formulae, R²⁹, R³⁰ and R³¹ each independently represents ahydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, anaryl group or an arylalkyl group, and a, b, c, d, m, n, o and p eachrepresents an integer representing the number of repeating unit.

As to the compounding amounts of the binder polymer and the compound(1), the amount of compound (1) is properly selected in the range ofusually from 10 to 1000 parts by weight, preferably from 30 to 500 partsby weight, more preferably from 40 to 200 parts by weight, per 100 partsby weight of the binder polymer.

The solvent for dissolving both the compound (1) and the binder polymeris not particularly limited, but organic solvents are preferred.Examples thereof include alcohols such as methanol, ethanol andisopropanol; ketones such as acetone, methyl ethyl ketone andcyclohexanone; amides such as N,N-dimethylformamide andN,N-dimethylacetamide; sulfoxides such as dimethylsulfoxide; ethers suchas tetrahydrofuran, dioxane, dioxolan, ethylene glycol dimethyl ether,diethyl ether, diisopropyl ether and tert-butyl methyl ether; esterssuch as ethyl acetate and methyl acetate; aliphatic halogenatedhydrocarbons such as methylene chloride, chloroform, 1,2-dichloroethane,dichloroethylene, carbon tetrachloride and trichloroethylene; aromatichalogenated hydrocarbons such as chlorobenzene and dichlorobenzene;aromatic hydrocarbons such as benzene, toluene and xylene; and aliphatichydrocarbons such as pentane, hexane, heptane, octane and cyclohexane.These solvents may be used independently or in a proper combination oftwo or more of them.

Application of the compound (1) on the electrically conductive supportor the charge generating layer is preferably conducted by, for example,dissolving or dispersing the compounds (1), the binder polymer, and, ifnecessary, other charge transporting material to be describedhereinafter and various additives to be described hereinafter to preparea coating solution or dispersion and applying the resultant solution ordispersion according to a known coating method. As a method fordispersing the ingredients, there may be employed a general dispersingmethod of using a ball mill, a sand mill, an attritor, a vibration millor an ultrasonic dispersing machine. As a coating method, there areillustrated, for example, a dip coating method, a spray coating method,a spinner coating method, a wire bar coating method, a blade coatingmethod, a roller coating method and a curtain coating method. The chargetransporting layer is formed by drying after the coating procedure.Drying of the coated film is preferably conducted by heat-drying afterdrying at room temperature. The heat-drying is preferably conducted at atemperature of 30 to 200° C. for a period of from 5 minutes to 2 hourswith or without sending air.

As has been described hereinbefore, in the charge transporting layer ofthe electrophotographic photoreceptor in accordance with the invention,other charge transporting materials may be used, as needed, incombination with the compound (1). Examples of the other chargetransporting material include hydrazone compounds represented by thefollowing formula (O) (e.g., JP-B-55-42380, JP-A-60-340999, andJP-A-61-23154), triphenylamine dimmers represented by the followingformula (P) (e.g. JP-B-58-32372), distyryl compounds represented by thefollowing formula (O) (e.g. U.S. Pat. No. 3,873,312),tetraphenylbutadiene series compounds, and triphenylmethanes. However,the other charge transporting materials to be used in combination withthe compound (1) may be any of those which have conventionally beenknown as charge transporting materials for electrophotographicphotoreceptors and are not limited only to the above-illustrated ones.

In the above formula (O), R⁴¹ and R⁴² may be the same or different, andeach represents a lower alkyl group, an aryl group optionally having asubstituent or an aralkyl group optionally having a substituent, R⁴³ andR⁴⁴ may be the same or different, and each represents a lower alkylgroup optionally having a substituent, an aryl group optionally having asubstituent, an aralkyl group optionally having a substituent or ahetero ring group optionally having a substituent, with R⁴³ and R⁴⁴optionally being connected to each other to form a ring, R⁴⁵ representsa hydrogen atom, a lower alkyl group, an aryl group optionally having asubstituent, an aralkyl group optionally having a substituent, a loweralkoxy group or a halogen atom, with R⁴⁵ and R⁴¹ or R⁴² being optionallyconnected to each other to form a ring.

In the above formula (P), R⁵¹ to R⁶² may be the same or different andeach represents a hydrogen atom, a lower alkyl group, a lower alkoxygroup, a halogen atom-substituted lower alkoxy group, an aryl groupoptionally having a substituent or a halogen atom.

In the above formula (O), R⁷¹ to R⁷⁴ may be the same or different andeach represents a lower alkyl group or an aryl group optionally having asubstituent, Ar₁, Ar₂ and Ar₃ may be the same or different and eachrepresents a phenylene group optionally having one or more substituentsselected from among a lower alkyl group, a lower alkoxy group, anaryloxy group and a halogen atom.

In the charge transporting layer of the electrophotographicphotoreceptor of the invention may be incorporated, as needed, variousadditives in order to more improve charge properties, stability ofcoating solutions and durability of the photoreceptor. Examples of theadditives include plasticizers such as biphenylene compounds,m-terphenyl and dibutyl terephthalate described in JP-A-6-332206;surface lubricants such as silicone oil, graft type silicone polymer andvarious fluorocarbons; charge stabilizers such as dicyanovinyl compoundsand carbazole derivatives; monophenol series antioxidants such as2,6-di-tert-butyl-4-methylphenol; bisphenol series antioxidants; amineseries antioxidants such as 4-diazabiicyclo[2,2,2]octane; salicylic acidseries antioxidants; antioxidants such as tocophenol; UV ray absorbents;and sensitizing agents.

The thickness of the charge transporting layer of theelectrophotographic photoreceptor of the invention is properly selectedin the range of usually from 5 to 40 μm, preferably from 10 to 30 μm.

The thus formed charge transporting layer is electrically connected tothe charge generating layer, and thus it functions to receive carriersinjected from the charge generating layer in the presence of an electricfield and transport the carriers to the other surface of the chargetransporting layer. As has been described hereinbefore, the chargetransporting layer may be laminated on or under the charge generatinglayer, but it is desirable for the charge generating layer to belaminated on the charge generating layer.

On the other hand, in the lamination type electrophotographicphotoreceptor, the charge generating layer is provided together with thecharge transporting layer. As is the same with the charge transportinglayer, the charge generating layer is formed by vacuum deposition orcoating on an electrically conductive support or on the chargetransporting layer. As the charge generating materials to be used in thecharge generating layer of the electrophotographic photoreceptor of theinvention, any of those may be used which have conventionally been usedas charge generating material for electrophotographic photoreceptors.Examples of the charge generating materials to be used in theelectrophotographic photoreceptor of the invention include inorganiccharge generating materials such as selenium, selenium-tellurium andamorphous silicon and organic charge generating materials such ascationic dyes (e.g., pyrylium salt series dyes, thiapyrylium seriesdyes, azulenium salt series dyes, thiacyanine series dyes andquinocyanine series dyes), squalium salt series pigments, phthalocyanineseries pigments, anthanthrone series pigments, polycyclic quinonepigments (e.g., dibenzpyrene quinone series pigments and pyranthroneseries pigments), indigo series pigments, quinacridone series pigments,azo series pigments and pyrrolopyrrole series pigments. These chargegenerating materials may be used independently or in a propercombination of two or more of them. Of the charge generating materials,organic charge generating materials are preferred, and particularlypreferred are those organic charge generating materials which aredescribed in Chemical Review (Chem. Rev.), 1993, vol. 93, pp. 449-486.Specifically, phthalocyanine series pigments, azo series pigments,perylene series compounds and polycyclic quinone series compounds areillustrated as preferred ones. In addition, any material that can absorblight and generate charge in a high yield other than these may be usedas well.

The phthalocyanine series pigments, azo pigments, perylene seriespigments and polycyclic quinone series compounds to be preferably usedin combination with the compound (1) of the charge transporting materialof the invention are more specifically described below. First, examplesof the phthalocyanine series pigments include alkoxytitaniumphthalocianine (Ti(OR)₂Pc), oxotitanium phthalocyanine (TiOPc), copperphthalocyanine (CuPc), metal-free phthalocyanine (H₂Pc), hydroxygalliumphthalocyanine (HOGaPc), vanadyl phthalocyanine (VOPc) and chloroindiumphthalocyanine (ClInPc). Still more specifically, as TiOPc, there areillustrated α-TiOPc, β-TiOPc, y-TiOPc, m-TiOPc, Y-TiOPc, A-TiOPc,B-TiOPc and amorphous TiOPc and, as H₂Pc, there are illustrated α-H₂Pc,β-H₂Pc, τ-H₂Pc and x-H₂Pc.

Azo pigments include mono-azo compounds, bis-azo compounds and tris-azocompounds. As preferred azo pigments, there are illustrated, forexample, bis-azo compounds represented by the following formulae (R),(S) and (T) and tris-azo compounds represented by the formula (U).Bis-azo Compounds:

Tris-azo Compounds:

As the perylene compounds, there are illustrated, for example, theperylene series compounds represented by the following formula (V):

wherein R represents a hydrogen atom, a lower alkyl group or an arylgroup optionally having a substituent.

As the polycyclic quinone series compounds, there are illustrated, forexample, the polycyclic quinone series compounds represented by thefollowing formula (W):

Formation of the charge generating layer by application may be conductedby dissolving or dispersing a charge generating material in a solventtogether with a binder polymer and, if necessary, various additives toprepare a coating solution, applying it onto an electrically conductivesupport or a charge transporting layer, and drying the coat, as is thesame with formation of the charge transporting layer. The binder polymerand other additives to be used here may be the same as those which havebeen referred to with respect to formation of the charge transportinglayer. Also, specific methods and conditions for forming the layer maybe the same as those employed for forming the charge transporting layer.

Also, in the single-layer electrophotographic photoreceptor of theinvention, a light-sensitive layer containing both a charge transportingmaterial including at least compound (1) and a charge generatingmaterial is provided on an electrically conductive support. Methods forforming the light-sensitive layer containing both the chargetransporting material and the charge generating material and conditionsfor forming the layer may be the same as the above-mentioned methods andconditions for forming the charge transporting layer and the chargegenerating layer. As the charge transporting material, the chargegenerating material, the binder polymer and various additives to be usedhere, the same ones as are employed for forming the charge transportinglayer and the charge generating layer of the above-mentioned functionseparated type electrophotographic photoreceptor.

Further, as the electrically conductive support to be used in theelectrophotographic photoreceptor of the invention, there areillustrated a sheet-shape or drum-shape electrically conductive supportmade of a metal such as copper, aluminum, silver, iron, zinc or nickelor an alloy thereof, an electrically conductive support made byvacuum-depositing or electrolytic plating of these metals on a plasticfilm or cylinder, and an electrically conductive support made byproviding a layer of electrically conductive polymer or electricallyconductive oxide such as indium oxide or tin oxide on a support such asglass, paper or plastic film by coating or vacuum deposition.

In the electrophotographic photoreceptor of the invention, an interlayer7 having barrier function or adhesion function may be provided, asneeded, between the conductive support and the light-sensitive layerprovided thereon as shown in FIGS. 4 to 6. The interlayer is provided onthe electrically conductive support for the purpose of preventing imagedefects in reversal development process, coating surface defects on theconductive support, improving chargability, improving adhesionproperties of the light-sensitive layer, and improving coatingproperties of the light-sensitive layer. In the case of forming theinterlayer 7, the aforesaid light-sensitive layer is provided on theinterlayer 7. As the material for forming the interlayer 7, there areillustrated, for example, polyvinylalcohol, nitrocellulose, casein,ethylene/acrylic acid copolymer, polyamide such as nylon, polyurethane,gelatin and aluminum oxide. The interlayer 7 can be formed by mixing theinterlayer-forming material, the above-mentioned solvent and, as needed,metal oxide such as titanium oxide, followed by the same method as withthe aforementioned charge transporting layer or the like. The thicknessof the interlayer is properly selected in a range of usually from 0.1 to5 pm, preferably from 0.5 to 3 μm.

Also, in the electrophotographic photoreceptor of the invention, aprotective layer may be formed by coating, as needed, on thelight-sensitive layer. This protective layer is provided for the purposeof, for example, improving wear resistance of the light-sensitive layeror preventing adverse influence of ozone or nitrogen oxide on thelight-sensitive layer.

The compound (1) to be used in the invention as a charge transportingmaterial for use in an electrophotographic photoreceptor shows highcharge mobility, and the charge transporting layer or thelight-sensitive layer containing it permits to form a uniform coat andattain a high sensitivity and a low residual potential. In addition, thecompound (1) shows good coating properties upon forming the coat and hasno problems such as eduction of crystals upon forming the chargetransporting layer or light-sensitive layer by coating. Thus, theinvention enables one to obtain a practical electrophotographicphotoreceptor having excellent electrophotographic properties of showinga high sensitivity and a low residual potential and having no pinholesand educed crystals in the formed light-sensitive layer, thus showinggood light-sensitive properties and good durability.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is now described more specifically by reference toSynthesis Examples, Examples and Comparative Examples which, of course,do not limit the invention in any way.

Additionally, measuring apparatuses and measuring conditions employed inSynthesis Examples are described below.

[¹H-NMR]

Apparatus: Model DRX-500 apparatus (500 MHz) made by Bruker company.

Internal standard substance: tetramethylsilane

Measurement: in heavy chloroform

[Mass analysis (MASS)]

Apparatus: Hitachi M-80B (Hitachi Ltd.)

SYNTHESIS EXAMPLE 1 Synthesis of Compound 1-1 [Compound of the Formula(1) Wherein R¹ to R⁵═H and R⁶═H]

(1) Synthesis of 4-bromostilbene [4a; compound of the formula (4) in thesynthesis scheme 1 wherein R¹ to R⁵═H, R⁶═H and X═Br]

18 g (0.16 mol) of potassium tert-butoxide was gradually added at 30 to50° C. to a solution of 15.8 g (0.149 mol) of benzaldehyde and 40.6 g(0.132 mol) of diethyl p-bromobenzylphosphite in 60 ml ofN,N-dimethylformamide. Further, 40 ml of N,N-dimethylformamide was addedthereto, and the solution was stirred at room temperature for 2 hours toreact. The reaction solution was poured into water, extracted with butylacetate and, after washing twice with water, the extract was dried overmagnesium sulfate and concentrated to obtain 33.9 g of crude crystals.Recrystallization of the thus obtained crude crystals fromtoluene-isopropanol (hereinafter abbreviated as “IPA”) yielded 29.0 g ofan end product. Yield: 84.8%; mp: 131-133° C.

¹H-NMR: 7.07 (ABq, d=16.3 Hz, 2H), 7.28 (t, J=7.4 Hz, 1H), 7.32-7.41 (m,4H), 7.45-7.52 (m, 4H)

MS: 258, 178

(2) Synthesis of Compound 1-1

In a 10-ml eggplant type flask, 8 mg (0.036 mmol) of palladium acetateand 34 mg (0.110 mmol) of a phosphorus ligand represented by thefollowing formula (8) (see JP-A-2002-187894) were charged, and 3 ml ofdioxane was added thereto in an atmosphere of nitrogen, followed byheating the mixture to dissolve, thus a catalyst solution beingprepared. Subsequently, 2.0 g (18.5 mmol) of m-phenylenediamine[compound (7) in the synthesis scheme 1], 20 g (77.2 mmol) of4-bromostilbene obtained in the above (1) and 7.8 g (81.2 mmol) ofsodium tert-butoxide were charged in a 200-ml flask, and 50 ml oftoluene was added thereto in an atmosphere of nitrogen. Theabove-mentioned catalyst solution was added thereto at room temperatureunder stirring using a syringe, followed by stirring the mixture forfurther 10 hours under reflux to react. The reaction solution was pouredinto water, extracted with toluene and, after washing twice with water,the extract was dried over magnesium sulfate and concentrated to obtain15.57 g of crude crystals. Recrystallization of the thus obtained crudecrystals from toluene yielded 12.57 g of an end product. Yield; 82.8%;mp: 222-225° C.

¹H-NMR: 6.78 (dd, J=8.1 Hz, J=2.2 Hz, 2H), 6.89 (t, J=2.2 Hz, 1H),6.98-7.04 (m, 7H), 7.09 (d, J=8.7 Hz, 8H), 7.07-7.10 (m, 1H), 7.15 (t,J=8.1 Hz, 1H), 7.23 (t, J=7.3 Hz, 4H), 7.31 (t, J=7.8 Hz, 8H), 7.39 (d,J=8.6 Hz, 8H), 7.45 (d, J=7.2 Hz, 8H)

MS: 820, 602

SYNTHESIS EXAMPLE 2 Synthesis of Compound 1-2 [Compound of the Formula(1) Wherein R′ or R⁵=Me and R⁶═H]

(1) Synthesis of 4-bromo-2′-methylstilbene [4b; compound of the formula(4) in the synthesis scheme 1 wherein R¹=Me, R² to R⁵═H, R⁶═H, and X═Br]

A mixed solution of 23 g (0.124 mol) of p-bromobenzaldehyde [5a;compound of the formula (5) in the synthesis scheme 1 wherein X═Br;hereinafter the same] and 33 g (0.136 mol) of diethylo-methylbenzylphosphite [6a; compound of the formula (6) in thesynthesis scheme 1 wherein R¹=Me, R² to R⁵═H, R⁶═H, and R⁷=Et] in 70 mlof N,N-dimethylformamide was gradually added to a suspension of 5.7 g(0.143 mol) of 60% sodium hydride in 30 ml of N,N-dimethylformamide at20 to 30° C. After stirring the mixture for 1 hour at room temperatureto react, the reaction solution was poured into water, extracted withtoluene and, after washing with water, the extract was dried overmagnesium sulfate and concentrated to obtain 36.99 g of crude crystals.Recrystallization of the thus obtained crude crystals from IPA yielded24.95 g of an end product.

Yield: 73.7%; mp: 67-68° C.

¹H-NMR: 2.41 (s, 3H), 6.92 (d, J=16.2 Hz, 1H), 7.17-7.22 (m, 3H), 7.31(d, J=16.1 Hz, 1H), 7.38 (d, J=8.4 Hz, 2H), 7.49 (d, J=8.5 Hz, 2H),7.55-7.59 (m, 1H)

MS: 274, 272, 193, 178, 116, 91

(2) Synthesis of Compound 1-2

A catalyst solution prepared in the same manner as in (2) of SynthesisExample 1 by mixing 10 mg (0.0445 mmol) of palladium acetate, 40 mg(0.129 mmol) of the phosphorus ligand represented by the foregoingformula (8) and 3 ml of dioxane was added to a solution of 1.0 g (9.2mmol) of m-phenylenediamine [compound (7) in the synthesis scheme 1],10.5 g (38.4 mmol) of 4-bromo-2′-methylstilbene (4b) and 4.0 g (41.6mmol) of sodium tert-butoxide in 40 ml of toluene, followed by stirringthe mixture for 10 hours under reflux to react. The reaction solutionwas poured into water, extracted with toluene and, after washing twicewith water, the extract was dried over magnesium sulfate andconcentrated to obtain 8.63 g of crude crystals. The resultant crudecrystals were purified through silica gel column chromatography (eluent:toluene), and further recrystallized from toluene to obtain 4.89 g of anend product. Yield: 60.5%; mp: 218-220° C.

¹H-NMR: 2.40 (s, 12H), 6.79 (dd, J=8.1 Hz, J=2.2 Hz, 2H), 6.91-6.95 (m,5H), 7.09 (d, J=8.6 Hz, 8H), 7.14-7.19 (m, 13H), 7.21 (s, 2H), 7.23 (s,2H), 7.40 (d, J=8.6 Hz, 8H), 7.52-7.55 (m, 4H)

MS: 878

SYNTHESIS EXAMPLE 3 Synthesis of Compound 1-3 [Compound of the Formula(1) Wherein R² or R⁴=Me, R¹ to R⁵ Other than R² or R⁴═H, and R⁶═H]

(1) Synthesis of 4-bromo-3′-methylstilbene [4c; compound of the formula(4) in the synthesis scheme 1 wherein R² or R⁴=Me, R¹ to R⁵ other thanR² or R⁴═H, R⁶═H, and X═Br]

8.5 g (0.213 mol) of 60% sodium hydride, 35 g (0.189 mol) ofp-bromobenzaldehyde (5a) and 50 g (0.206 mol) of diethylm-methylbenzylphosphite [6b; compound of the formula (6) in thesynthesis scheme 1 wherein R² or R⁴=Me, R¹ to R⁵ other than R² or R⁴═H,R⁶═H, and R⁷=Et] were mixed, and reaction and after-treatment wereconducted in the same manner as in (1) of Synthesis Example 2 to obtain65 g of crude crystals. Recrystallization of the thus obtained crudecrystals from toluene (95 g)-IPA (100 ml) yielded 41.94 g of an endproduct. Yield: 81.2%; mp: 110-111° C.

¹H-NMR: 2.39 (s, 3H), 6.99-7.11 (m, 3H), 7.21-7.26 (m, 1H), 7.29-7.33(m, 2H), 7.37 (d, J=8.5 Hz, 2H), 7.48 (d, J=8.5 Hz, 2H)

MS: 274, 272, 193, 178, 165, 152, 115, 91

(2) Synthesis of Compound 1-3

A catalyst solution prepared in the same manner as in (2) of SynthesisExample 1 by mixing 4 mg (0.018 mmol) of palladium acetate, 17 mg (0.055mmol) of the phosphorus ligand represented by the foregoing formula (8)and 2 ml of dioxane was added to a solution of 1.0 g (9.25 mmol) ofm-phenylenediamine [compound (7) in the synthesis scheme 1], 10.5 g(38.4 mmol) of 4-bromo-3′-methylstilbene (4c) and 3.9 g (40.6 mmol) ofsodium tert-butoxide in 50 ml of toluene, followed by stirring themixture for 10 hours under reflux to react. The reaction solution waspoured into water, extracted with toluene and, after separation, thetoluene layer was washed twice with water, dried over magnesium sulfateand concentrated to obtain 8.39 g of crude crystals. The resultant crudecrystals were purified through silica gel column chromatography (eluent:toluene) to obtain 5.44 g of an end product. Further, recrystallizationof the product from toluene yielded 5.12 g of an end product. Yield:63.1%; mp: 178-180° C.

¹H-NMR: 2.32 (s, 12H), 6.77 (dd, J=8.0 Hz, J=2.2 Hz, 2H), 6.92 (t, J=2.1Hz, 1H), 6.94-7.06 (m, 11H), 7.08 (d, J=8.7 Hz, 8H), 7.12-7.21 (m, 6H),7.23-7.30 (m, 8H), 7.38 (d, J=8.6 Hz, 8H)

MS: 878

Synthesis EXAMPLE 4 Synthesis of Compound 1-9 [Compound of the Formula(1) Wherein R¹ to R⁵═H and R⁶=Me]

(1) Synthesis of 1-(4-bromophenyl)-2-methyl-2-phenylethylene [4d;compound of the formula (4) in the synthesis scheme 1 wherein R¹ toR⁵═H, R⁶=Me and X═Br]

3.6 g (90.0 mmol) of 60% sodium hydride, 15 g (81.1 mmol) ofp-bromobenzaldehyde [5a; compound of the formula (5) in the synthesisscheme 1 wherein X═Br] and 20.6 g (85.0 mmol) of diethyl1-phenylethylphosphite [6c; compound of the formula (6) in the synthesisscheme 1 wherein R¹ to R⁵═H, R⁶=Me and R⁷=Et] were mixed, and reactionand after-treatment were conducted in the same manner as in (1) ofSynthesis Example 2 to obtain 22.5 g of crude crystals.Recrystallization of the thus obtained crude crystals from IPA yielded13.29 g of an end product. Yield: 60.0%; mp: 72-80° C.

¹H-NMR: 2.25 (s, 3H), 6.74 (s, 1H), 7.21 (d, J=8.3 Hz, 2H), 7.28-7.31(m, 1H), 7.38 (t, J=7.8 Hz, 2H), 7.50 (t, J=8.5 Hz, 4H)

MS: 274, 272, 207, 178, 153, 129, 105, 71

(2) Synthesis of Compound 1-9

A catalyst solution prepared in the same manner as in (2) of SynthesisExample 1 by mixing 4 mg (0.018 mmol) of palladium acetate, 17 mg (0.055mmol) of the phosphorus ligand represented by the foregoing formula (8)and 2 ml of dioxane was added to a solution of 1.25 g (11.51 mmol) ofm-phenylenediamine [compound (7) in the synthesis scheme 1], 13 g (47.6mmol) of 1-(4-bromophenyl)-2-methyl-2-phenyhlethylene (4d) and 4.8 g(50.0 mmol) of sodium tert-butoxide in 50 ml of xylene, followed bystirring the mixture for 10 hours at 100° C. to react. The reactionsolution was poured into water, extracted with toluene and, afterwashing twice with water, the extract was dried over magnesium sulfateand concentrated to obtain 9.71 g of an oily product. The resultant oilyproduct was purified through silica gel column chromatography (eluent:toluene/hexane=1/1) to obtain 5.2 g of an end product. Further,recrystallization of the product from a toluene-hexane mixed solventyielded 3.71 g of an end product. Yield: 36.6%; mp: 151-152° C.

¹H-NMR: 2.27 (s, 12H), 6.75-6.79 (m, 6H), 6.97 (t, J=2.1 Hz, 1H), 7.12(d, J=8.7 Hz, 8H), 7.24-7.29 (m, 13H), 7.34 (t, J=7.9 Hz, 8H), 7.48 (d,J=7.1 Hz, 8H)

MS: 878

SYNTHESIS EXAMPLE 5 Synthesis of Compound 1-11 [Compound of the Formula(1) Wherein R¹ to R⁵═H and R⁶=Ph]

(1) Synthesis of 1-(4-bromophenyl)-2-diphenylethylene [4e; compound ofthe formula (4) in the synthesis scheme 1 wherein R¹ to R⁵═H, R⁶=Ph andX═Br]

20.0 g (0.1081 mol) of p-bromobenzaldehyde [5a; compound of the formula(5) in the synthesis scheme 1 wherein X═Br] and 35.9 g (90%, 0.118 mol)of diethyl diphenylmethylphosphite [6d; compound of the formula (6) inthe synthesis scheme 1 wherein R¹ to R⁵═H, R⁶=Ph and R⁷=Et] weredissolved in 60 ml of DMF (dimethylformamide), and 15 g (0.134 mol) ofpotassium tert-butoxide was gradually added thereto. After stirring themixture overnight at room temperature, it was poured into water,extracted with toluene, washed twice with water, dried over magnesiumsulfate, and concentrated to obtain 36.99 g of a concentrate. Theconcentrate was purified by reduced pressure distillation to obtain 23.5g of an end product. Yield: 64.8%; bp: 160-165° C./1 mmHg.

¹H-NMR: 6.89 (d, J=8.4 Hz, 2H), 6.90 (s, 1H), 7.19-7.21 (m, 2H), 7.26(d, J=8.5 Hz, 2H), 7.30-7.37 (m, 8H)

MS: 334, 253, 239, 226, 215, 202, 189, 178, 165, 151, 139, 126, 113,101, 88, 77, 63, 51

(2) Synthesis of Compound 1-11

A catalyst solution was prepared from 10 mg (0.027 mmol) ofallylpalladium chloride dimer, 31.0 mg (0.10 mmol) of the phosphorusligand represented by the foregoing formula (8) and 2 ml of dioxane, andwas added to a solution of 0.5 g (4.6 mmol) of m-phenylenediamine (7),6.8 g (20.3 mmol) of 1-(4-bromophenyl)-2-diphenylethylene (4e) and 2.0 g(20.8 mmol) of sodium tert-butoxide in 30 ml of toluene. The reactionwas conducted overnight at 100° C., and the mixture was poured intowater. Toluene and ethyl acetate were added thereto to extract. Theorganic layer was washed twice with water, dried over magnesium sulfate,and concentrated to obtain 5.76 g of a product, which was furtherpurified through silica gel column chromatography (eluent:toluene/hexane=1/1) to obtain 3.1 g of an oily product. Crystallizationof the product from a toluene-hexane mixed solvent (8 ml/10 ml) yielded2.86 g of an end product. Yield: 55.2%, mp: 131-132° C.

¹H-NMR: 6.62 (dd, J=8.1 Hz, J-2.0 Hz, 2H), 6.70 (s, 1H), 6.75 (d, J=8.7Hz, 8H), 6.84 (d, J=8.7 Hz, 8H), 6.89 (s, 4H), 7.01 (t, J=8.1 Hz, 1H),7.15-7.36 (m, 40H)

MS: 1126

EXAMPLE 1

One part by weight of α-oxytitanyl phthalocyanine [made by SANYO COLORWORKS, LTD., α-TiOPc] was added to a binder polymer solution obtained bydissolving 1 part by weight of a butyral resin [Poly(vinyl butyral)BL-1, made by Sekisui Chemical Co., Ltd., hereinafter the same] in 30parts by weight of tetrahydrofuran, and was dispersed in a vibrationmill for 5 hours together with glass beads. This dispersion was appliedonto a sheet prepared by vacuum depositing aluminum on a polyethyleneterephthalate (hereinafter abbreviated as “PET”) film using a wire bar,followed by drying at 100° C. for 2 hours to form a charge generatinglayer of about 2 μm in thickness.

Subsequently, 1 part by weight of compound 1-3 obtained in SynthesisExample 3 and 1 part by weight of a polycarbonate resin, Panlite TS-2020[made by TEIJIN CHEMICALS LTD.; hereinafter the same] were mixed anddissolved in 8 parts by weight of 1,2-dichloroethane. This solution wasapplied onto the formerly formed charge generating layer using a doctorblade, and dried at 80° C. for 3 hours to form a charge transportinglayer of about 20 μm in thickness, thus an electrophotographicphotoreceptor A of the invention being prepared.

EXAMPLE 2

An electrophotographic photoreceptor B of the invention was prepared inthe same manner as in Example 1 except for using compound 1-9 in placeof compound 1-3.

CHARACTERISTICS TEST EXAMPLE 1

The electrophotographic characteristics of the electrophotographicphotoreceptors A and B obtained in Examples 1 and 2 were measuredaccording to a static system using an electrostatic recording testermodel EPA-8200 (made by Kawaguchi Electric Works Co., Ltd.; hereinafterthe same). That is, each of the electrophotographic photoreceptors A andB was charged by conducting corona discharge of −6 KV, and the surfacepotential V_(o), (unit: −V) was measured. After keeping them for 5seconds in a dark room (surface potential at this stage: Vi (unit: −V)),they were irradiated with a 5-lux light from a tungsten halogen lamp todetermine a half decay exposure E_(1/2) (lux·sec) necessary for reducingthe surface potential Vi to a half level, a ⅙ decay exposure E_(1/6)(lux·sec) necessary for reducing the surface potential to one-sixth, andsurface residual potential V_(R10) (−V) after irradiating with a 5-luxlight for 10 seconds. Results thus obtained are shown in Table 2. TABLE2(A) Charge Charge Generating Transporting V_(o) Vi V_(R10) MaterialMaterial (−V) (−V) (−V) Example 1 (A) α-TiOPc compound 1-3 830 668 3Example 2 (B) α-TiOPc compound 1-9 934 740 0

TABLE 2(B) E_(1/2) (lux · sec) E_(1/6) (lux · sec) Example 1 (A) 0.470.78 Example 2 (B) 0.32 0.57

EXAMPLE 3

One part by weight of β-oxytitanyl phthalocyanine [made by SANYO COLORWORKS, LTD., β-TiOPc] was added to a binder polymer solution obtained bydissolving 1 part by weight of a butyral resin [Poly (vinyl butyral)BL-1] in 30 parts by weight of tetrahydrofuran, and was dispersed in avibration mill for 5 hours together with glass beads. This dispersionwas applied onto a sheet comprising a PET film having vacuum depositedthereon aluminum, using a wire bar, followed by drying at 100° C. for 2hours to form a charge generating layer of about 2 μm in thickness.

Subsequently, 1 part by weight of compound 1-3 obtained in SynthesisExample 3 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor C of the invention being prepared.

EXAMPLE 4

A charge generating layer was formed using β-oxytitanyl phthalocyanine(β-TiOPc) on a sheet prepared by vacuum depositing aluminum on a PETfilm in the same manner as in Example 3. Subsequently, 1 part by weightof compound 1-9 obtained in Synthesis Example 4 and 1 part by weight ofa polycarbonate resin, Panlite TS-2020 were mixed and dissolved in 8parts by weight of 1,2-dichloroethane. This solution was applied ontothe formerly formed charge generating layer using a doctor blade, anddried at 80° C. for 3 hours to form a charge transporting layer of about20 μm in thickness, thus an electrophotographic photoreceptor D of theinvention being prepared.

COMPARATIVE EXAMPLE 1

A charge generating layer was formed on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 3using β-oxytitanyl phthalocyanine (β-TiOPc).

Subsequently, 1 part by weight of comparative compound 1 represented bythe following formula and 1 part by weight of a polycarbonate resin,Panlite TS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor a being prepared.

CHARACTERISTICS TEST EXAMPLE 2

The electrophotographic characteristics of the electrophotographicphotoreceptors C, D and a obtained respectively in Examples 3 and 4 andComparative Example 1 were measured by a static system in the samemanner as in Characteristics Test Example 1 using an electrostaticrecording tester model EPA-8200. Results thus obtained are shown inTable 3. TABLE 3(A) Charge Charge Generating Transporting V_(o) ViV_(R10) Material Material (−V) (−V) (−V) Example 3 (C) β-TiOPc compound1-3 501 361 0 Example 4 (D) β-TiOPc compound 1-9 542 417 0 Com. Ex. 1(a) β-TiOPc comparative 722 538 3 compound 1

TABLE 3(B) E_(1/2) (lux · sec) E_(1/6) (lux · sec) Example 3 (C) 0.892.01 Example 4 (D) 0.90 2.03 Com. Ex. 1 (a) 1.01 2.15

As is apparent from Table 3, it is seen that the electrophotograpicphotoreceptors C and D of the invention showed a higher sensitivity(smaller value of E_(1/2) and E_(1/6)) and smaller residual potentialthan those of the electrophotographic photoreceptor a using thecomparative compound 1. These data demonstrate the excellence of theelectrophotographic photoreceptors of the invention.

EXAMPLE 5

One part by weight of crystalline oxytitanyl phthalocyanine (TiOPccrystals) prepared according to the process described in JP-A-63-20365was added to a binder polymer solution obtained by dissolving 1 part byweight of a butyral resin [Poly (vinyl butyral) BL-1] in 30 parts byweight of tetrahydrofuran, and was dispersed in a vibration mill for 5hours together with glass beads. This dispersion was applied onto asheet prepared by vacuum depositing aluminum on a PET film, using a wirebar, followed by drying at 100° C. for 2 hours to form a chargegenerating layer of about 2 μm in thickness.

Subsequently, 1 part by weight of compound 1-3 obtained in SynthesisExample 3 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor E of the invention being prepared.

EXAMPLE 6

A charge generating layer of about 2 μm in thickness was formed usingcrystalline oxytitanyl phthalocyanine (TiOPc crystals) on a sheetprepared by vacuum depositing aluminum on a PET film in the same manneras in Example 5.

Subsequently, 1 part by weight of compound 1-9 obtained in SynthesisExample 4 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor F of the invention being prepared.

COMPARATIVE EXAMPLE 2

A charge generating layer (about 2 μm in thickness) was formed usingcrystalline oxytitanyl phthalocyanine (TiOPc crystals) on a sheetprepared by vacuum depositing aluminum on a PET film in the same manneras in Example 5.

Subsequently, 1 part by weight of comparative compound 2 represented bythe following formula and 1 part by weight of a polycarbonate resin,Panlite TS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor b being prepared.

CHARACTERISTICS TEST EXAMPLE 3

The electrophotographic characteristics of the electrophotographicphotoreceptors E, F and b obtained respectively in Examples 5 and 6 andComparative Example 2 were measured by a static system in the samemanner as in Characteristics Test Example 1 using an electrostaticrecording tester model EPA-8200. Results thus obtained are shown inTable 4. TABLE 4(A) Charge Charge Generating Transporting V_(o) ViV_(R10) Material Material (−V) (−V) (−V) Example 5 (E) TiOPc compound1-3 698 589 3 crystals Example 6 (F) TiOPc compound 1-9 713 570 0crystals Com. Ex. 2 (b) TiOPc comparative 787 678 15 crystals compound 2

TABLE 4(B) E_(1/2) (lux · sec) E_(1/6) (lux · sec) Example 5 (E) 0.410.87 Example 6 (F) 0.36 0.75 Com. Ex. 2 (b) 0.85 2.01

As is apparent from Table 4, it is seen that the electrophotographicphotoreceptors E and F of the invention showed a higher sensitivity(smaller value of E_(1/2) and E_(1/6)) and smaller residual potentialthan those of the electrophotographic photoreceptor b using thecomparative compound 2. These data demonstrate the excellence of theelectrophotographic photoreceptors of the invention.

EXAMPLE 7

One part by weight of x-type metal-free phthalocyanine (x-H₂Pc) wasadded to a binder polymer solution obtained by dissolving 1 part byweight of a butyral resin [Poly(vinyl butyral) BL-1] in 30 parts byweight of tetrahydrofuran, and was dispersed using a vibration mill for5 hours together with glass beads. This dispersion was applied onto asheet prepared by vacuum depositing aluminum on a PET film, using a wirebar, followed by drying at 100° C. for 2 hours to form a chargegenerating layer of about 2 μm in thickness.

Subsequently, 1 part by weight of compound 1-3 obtained in SynthesisExample 3 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor G of the invention being prepared.

EXAMPLE 8

A charge generating layer (about 2 μm in thickness) was formed usingx-type metal-free phthalocyanine (x-H₂Pc) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 7.

Subsequently, 1 part by weight of compound 1-9 obtained in SynthesisExample 4 and 1 part by weight of a polycarbonate resin, PanliteTS-2020made by TEIJIN CHEMICALS LTD. were mixed and dissolved in 8 parts byweight of 1,2-dichloroethane. This solution was applied onto theformerly formed charge generating layer using a doctor blade, and driedat 80° C. for 3 hours to form a charge transporting layer of about 20 μmin thickness, thus an electrophotographic photoreceptor H of theinvention being prepared.

COMPARATIVE EXAMPLE 3

A charge generating layer (about 2 μm in thickness) was formed usingx-type metal-free phthalocyanine (x-H₂PC) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 7.

Subsequently, 1 part by weight of comparative compound 3 represented bythe following formula and 1 part by weight of a polycarbonate resin,Panlite TS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor c being prepared.

COMPARATIVE EXAMPLE 4

A charge generating layer (about 2 μm in thickness) was formed usingx-type metal-free phthalocyanine (x-H₂PC) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 7.

Subsequently, 1 part by weight of the above-described comparativecompound 1 and 1 part by weight of a polycarbonate resin, PanliteTS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor d being prepared.

COMPARATIVE EXAMPLE 5

A charge generating layer (about 2 μm in thickness) was formed usingx-type metal-free phthalocyanine (x-H₂Pc) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 7.

Subsequently, 1 part by weight of the above-described comparativecompound 2 and 1 part by weight of a polycarbonate resin, PanliteTS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor e being prepared.

CHARACTERISTICS TEST EXAMPLE 4

The electrophotographic characteristics of the electrophotographicphotoreceptors G, H, c, d and e obtained respectively in Examples 7 and8 and Comparative Examples 3, 4 and were measured by a static systemusing an electrostatic recording tester model EPA-8200 in the samemanner as in Characteristics Test Example 1. Results thus obtained areshown in Table 5. TABLE 5(A) Charge Charge Generating Transporting V_(o)Vi V_(R10) Material Material (−V) (−V) (−V) Example 7 (G) x-H₂Pccompound 1-3 986 861 0 Example 8 (H) x-H₂Pc compound 1-9 1059 950 0 Com.Ex. 3 (c) x-H₂Pc comparative 1087 971 5 compound 3 Com. Ex. 4 (d) x-H₂Pccomparative 846 757 0 compound 1 Com. Ex. 5 (e) x-H₂Pc comparative 1066944 27 compound 2

TABLE 5(B) E_(1/2) (lux · sec) E_(1/6) (lux · sec) Example 7 (G) 0.791.54 Example 8 (H) 0.83 1.66 Com. Ex. 3 (c) 1.07 1.95 Com. Ex. 4 (d)1.07 2.08 Com. Ex. 5 (e) 1.34 3.27

As is apparent from Table 5, it is seen that the electrophotographicphotoreceptors G and H of the invention showed a higher sensitivity(smaller value of E_(1/2) and E_(1/6)) and smaller residual potentialthan those of the electrophotographic photoreceptors c, d and e usingrespectively the comparative compounds 3, 1 and 2. These datademonstrate the excellence of the electrophotographic photoreceptors ofthe invention.

EXAMPLE 9

One part by weight of τ-type metal-free phthalocyanine (τ-H₂Pc) wasadded to a binder polymer solution obtained by dissolving 1 part byweight of a butyral resin [Poly(vinyl butyral) BL-1] in 30 parts byweight of tetrahydrofuran, and was dispersed using a vibration mill for5 hours together with glass beads. This dispersion was applied onto asheet prepared by vacuum depositing aluminum on a PET film using a wirebar, followed by drying at 100° C. for 2 hours to form a chargegenerating layer of about 2 μm in thickness.

Subsequently, 1 part by weight of compound 1-3 obtained in SynthesisExample 3 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor I of the invention being prepared.

EXAMPLE 10

A charge generating layer (about 2 μm in thickness) was formed usingτ-type metal-free phthalocyanine (τ-H₂Pc) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 9.

Subsequently, 1 part by weight of compound 1-9 obtained in SynthesisExample 4 and 1 part by weight of a polycarbonate resin, Panlite TS-2020were mixed and dissolved in 8 parts by weight of 1,2-dichloroethane.This solution was applied onto the formerly formed charge generatinglayer using a doctor blade, and dried at 80° C. for 3 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor J of the invention being prepared.

COMPARATIVE EXAMPLE 6

A charge generating layer (about 2 μm in thickness) was formed usingτ-type metal-free phthalocyanine (τ-H₂Pc) on a sheet prepared by vacuumdepositing aluminum on a PET film in the same manner as in Example 9.

Subsequently, 1 part by weight of comparative compound 4 represented bythe following formula and 1 part by weight of a polycarbonate resin,Panlite TS-2020 were mixed and dissolved in 8 parts by weight of1,2-dichloroethane. This solution was applied onto the formerly formedcharge generating layer using a doctor blade, and dried at 80° C. for 3hours to form a charge transporting layer of about 20 μm in thickness,thus an electrophotographic photoreceptor f being prepared.

CHARACTERISTICS TEST EXAMPLE 5

The electrophotographic characteristics of the electrophotographicphotoreceptors I, J and f obtained respectively in Examples 9 and 10 andComparative Example 6 were measured by a static system using anelectrostatic recording tester model EPA-8200 in the same manner as inCharacteristics Test Example 1. Results thus obtained are shown in Table6. TABLE 6(A) Charge Charge Generating Transporting V_(o) Vi V_(R10)Material Material (−V) (−V) (−V) Example 9 (I) τ-H₂Pc compound 1-3 918714 2 Example 10 (J) τ-H₂Pc compound 1-9 859 659 16 Com. Ex. 6 (f)τ-H₂Pc comparative 475 149 29 compound 4

TABLE 6(B) E_(1/2) (lux · sec) E_(1/6) (lux · sec) Example 9 (I) 1.022.28 Example 10 (J) 1.05 2.48 Com. Ex. 6 (f) 4.59 too small to measure

As is apparent from Table 6, it is seen that the electrophotographicphotoreceptors I and J of the invention showed a higher sensitivity(smaller value of E_(1/2) and E_(1/6)) and smaller residual potentialthan those of the electrophotographic photoreceptor f using thecomparative compound 4. These data demonstrate the excellence of theelectrophotographic photoreceptors of the invention.

EXAMPLE 11

One part by weight of compound 1-3 obtained in Synthesis Example 3 and 1part by weight of a polycarbonate resin, Panlite TS-2020 were mixed anddissolved in 8 parts by weight of 1,2-dichloroethane. This solution wasapplied onto a sheet prepared by vacuum depositing aluminum on a PETfilm using a doctor blade, and dried at 80° C. for 2 hours to form acharge transporting layer of about 20 μm in thickness, thus anelectrophotographic photoreceptor K of the invention being prepared.

EXAMPLE 12

An electrophotographic photoreceptor L was prepared in the same manneras in Example 11 except for using compound 1-9 obtained in SynthesisExample 4 in place of compound 1-3.

COMPARATIVE EXAMPLE 7

An electrophotographic photoreceptor g was prepared in the same manneras in Example 11 except for using the foregoing comparative compound 1in place of compound 1-3.

COMPARATIVE EXAMPLE 8

An electrophotographic photoreceptor h was prepared in the same manneras in Example 11 except for using the comparative compound 5 representedby the following formula in place of compound 1-3.

CHARACTERISTICS TEST EXAMPLE 6

The charge carrier mobility was measured with the electrophotographicphotoreceptors K, L, g and h obtained in Examples 11 and 12 andComparative Examples 7 and 8, respectively, by vacuum depositing asemi-transparent gold electrode on the charge transporting layer formedin each of these electrophotographic photoreceptors. Measurement of thecarrier mobility was conducted according to the time-of-flight method(see, for example, Somei Tanaka, Yasuhiro Yamaguchi and MasaakiYokoyama, Electrophotography, 29, p. 366 (1990)) using as a light sourcea nitrogen gas laser of 0.9 nsec in pulse half width and 337 nm inwave-length. Results of the measurement conducted at 25° C. and 25 V/μmare shown in Table 7. TABLE 7 Charge Transporting Carrier MobilityMaterial (cm²/Vs) Example 11 compound 1-3 2.81 × 10⁻⁵ Example 12compound 1-9 2.37 × 10⁻⁵ Com. Ex. 7 comparative compound 1 0.67 × 10⁻⁵Com. Ex. 8 comparative compound 5 0.98 × 10⁻⁵

As is apparent from Table 7, it is seen that the charge transportingmaterials to be used in the electrophotographic photoreceptor of theinvention showed larger carrier mobility than those of the comparativecompounds 1 and 5. These data demonstrate the excellence of theelectrophotographic photoreceptors of the invention.

Additionally, all of the charge transporting layers formed in Examples 1to 12 showed good coating properties, and none of them suffered eductionof crystals of the charge transporting material and formation ofpinholes.

ADVANTAGES OF THE INVENTION

The charge transporting materials of the invention for use inelectrophotographic photoreceptors have high carrier mobility, and theelectrophotographic photoreceptor of the invention using the chargetransporting material of the invention has good film stability, attainsa high sensitivity and a low residual potential, thus being industriallyexcellent.

INDUSTRIAL APPLICABILITY

As has been described hereinbefore, the electrophotographicphotoreceptor of the invention can advantageously be used as aphotoreceptor for use in a copying and/or recording apparatus based onelectrophotographic process such as an electrophotographic copyingmachine, a laser beam printer, a printer having a liquid crystalshutter, and an LED printer. Additionally, the charge transportingmaterials of the invention for use in electrophotographic photoreceptorsare advantageously used as charge transporting materials to be used inthe light-sensitive layer of these electrophotographic photoreceptors.

1. An electrophotographic photoreceptor which contains a compoundrepresented by the formula (1):

wherein R¹ to R⁵ each independently represents a hydrogen atom, an alkylgroup, a halogen atom, an alkoxy group, an aryl group or a substitutedaryl group, and R⁶ represents a hydrogen atom, an alkyl group, an arylgroup or a substituted aryl group.
 2. An electrophotographicphotoreceptor which contains a compound represented by the above formula(1) as a charge transporting material in the light-sensitive layerprovided on an electrically conductive support.
 3. Anelectrophotographic photoreceptor of lamination type having provided onan electrically conductive support a charge generating layer and acharge transporting layer, which contains a compound represented by theabove formula (1) as a charge transporting material.
 4. Anelectrophotographic photoreceptor of single layer type having providedon an electrically conductive support a layer containing both a chargegenerating material and a charge transporting material, which contains acompound represented by the above formula (1).
 5. A charge transportingmaterial for use in an electrophotographic photoreceptor, whichcomprises a compound represented by the above formula (1).